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1016Re: [GPSL] Last Weekend's ISU Flight

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paul.verhage@boiseschools.org

Oct 5, 2004

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> For the UNO BalloonSat flight, I believe the students used plastic tubing used to run water to things like ice makers in refrigerators, etc. Easily obtained from a hardware or home improvement store. To keep the tubing from sliding through the cube, a metal retaining clip (looks like a "C"

with flanges that grip the tube) was placed on both sides of the cube. This worked pretty well for us. The tube was flexible enough to keep the line from abrading. We also put a separate line from the top tracking payload to the bottom one so that if one of the BalloonSats did cut the load
line, the tracking payloads would remain tied together. There were no cameras in our BalloonSats so there were no issues with obscuring their view with another line.

>
> Has there been an issue with foam core satellites? I think foam core mount board would be a lot easier for the students to cut cleanly than styrofoam.

I'm using a polystyrene tube (3/8" diameter, I believe) for my BalloonSat tube. The
tube is manufactured straight. I can hot glue it to the 1/2" styrofoam BalloonSat.

I'm using 1/2" foam because it will be warmer and I believe easier to machine. As
long as I use a sharp exacto knife, I get clean cuts on the foam. The BalloonSat
should be stronger in foam than foamcore. I'll have some students make strenght
tests on the stuff in the next week. Also, the BalloonSat will be more protected from
water damage.

I coat my BalloonSat with Uline tape, a tape made for styrofoam gliders. It comes in
a variety of colors and is very lightweight. Especially when you compare it to the
aluminum tape used on some BalloonSats. With uline tape and 1/2" foam, I believe
my BalloonSat airframe is lighter.

I'll have my students run some tests and report back the results.

On using a three line suspension...
Using the single line suspension risks abrading the line and dropping the lower
BalloonSats, which is how my BalloonSat was lost. There are alternatives, as Mark
said. But if you use a three line suspension, you also reduce the rocking and
spinning experienced by the BalloonSats. The photos should be crisper as a result.
The reduced rocking and spinning also cuts down on the abrasion.